JP6546061B2 - Management apparatus and method - Google Patents

Description

  The present invention relates to a management apparatus and method.

  In recent years, base stations of small cells such as microcells, nanocells, picocells, femtocells, etc. have been installed. As a result, good communication quality can be maintained even in a place where radio waves from the nearest macro cell are hard to reach due to the influence of topography or buildings, or inside a building where radio waves from the outside are hard to reach.

  Interference among cells in uplink (hereinafter, referred to simply as uplink interference) is one of the problems when small cells are densely arranged. Uplink interference is interference by a signal that is in a nearby cell and reaches a base station of a target cell from a terminal that communicates with the base station. Uplink interference becomes stronger as the distance between base stations decreases, and may be more prominent when the small cells are densely arranged. Such uplink interference can be reduced by using the interference removal / reduction techniques as proposed in, for example, Non-Patent Documents 1, 2 and 3.

K. Balachandran, J. Kang, K. Karakayali, and K. Rege, “Networkcentric cooperation schemes for uplink interference management in cellular networks,” Bell Labs Technical Journal, vol. 18, no. 2, pp. 23. 36, Sept 2013. K. Lee, “Uplink interference alignment for two-cell mimo interference channels,” Vehicular Technology, IEEE Transactions on, vol. 62, no. 4, pp. 1861.1865, May 2013. Y. Sun, R. Jover, and X. Wang, “Uplink interference mitigation for the wireless network, IEEE Transactions on, vol. 11, no. 2, pp. 612.625, February 2012. K. Oltmann, R. Cavalcante, S. Stanczak, and M. Kasparick, “Interference identification in cellular networks via adaptive projected subgradient methods,” in Signals, Systems and Computers, 2013 Asilomar Conference on Nov 2013, pp. 1946.1950.

  However, uplink interference changes dynamically as the mobile terminal that is the interference source moves. Therefore, in order to make full use of the capability of the interference removal / reduction technique as proposed in Non-Patent Documents 1, 2 and 3, it is necessary to specify an interference source.

  The present invention has been made in view of these problems, and an object thereof is to provide a technique capable of identifying an interference source of uplink interference or a technique for a terminal to perform control in consideration of the interference source.

  One embodiment of the present invention relates to a management device. The management apparatus is a management apparatus of a wireless communication system including a first base station and a second base station, and is transmitted from a signal received by the first base station by a terminal whose serving base station is the first base station. The second base station is acquired based on an acquisition unit for acquiring information on the power of the remaining part excluding the components of the received signal, schedule information on the second base station, and information on the power acquired by the acquisition unit. And an evaluation unit for evaluating interference from each of terminals serving as a serving base station to the first base station.

  Another aspect of the present invention is also a management device. The management apparatus is a management apparatus of a wireless communication system including a plurality of base stations, and includes an acquisition unit that acquires schedule information independently determined by each of the plurality of base stations, and a plurality of acquisition units acquired by the acquisition unit. The interference evaluation is performed using a plurality of schedule information specified by the specifying unit for the specifying unit that specifies a plurality of pieces of schedule information having a predetermined relationship from among the schedule information, and one of the plurality of base stations. And a request unit for requesting.

  Another aspect of the invention is a terminal. This terminal is a terminal that uses the first base station as a serving base station, and the first base station according to the schedule information acquisition unit that acquires schedule information from the first base station, and the schedule information acquired by the schedule information acquisition unit. And a management unit of a wireless communication system including a first base station and a second base station, comprising: a transmitter configured to transmit a signal to a station, a component of the signal transmitted by the terminal from the signal received by the first base station Information on the power of the remaining part excluding the second base station, and based on the schedule information on the second base station and the information on the acquired power, the second base station serving as the serving base station 1 Evaluate interference to the base station.

  Another aspect of the invention is a terminal. This terminal is a terminal that uses one of a plurality of base stations as a serving base station, and is acquired by a schedule information acquisition unit that acquires schedule information from one base station, and a schedule information acquisition unit. And a transmitter configured to transmit a signal to one base station according to the schedule information, and the management apparatus of the wireless communication system including the plurality of base stations acquires the schedule information independently determined by each of the plurality of base stations. And identifying a plurality of pieces of schedule information having a predetermined relationship among the plurality of pieces of schedule information acquired, and using the plurality of pieces of schedule information identified by the identifying unit in one of the plurality of base stations. Request to make an evaluation of

  In the present invention, any combination of the above-described constituent elements, and one in which the constituent elements and expressions of the present invention are mutually replaced between an apparatus, a method, a system, a computer program, a recording medium storing a computer program, etc. It is effective as an aspect of

  According to the present invention, it is possible to identify an interference source of uplink interference or allow a terminal to perform control in consideration of the interference source.

It is a typical explanatory view for explaining the principle of an embodiment. It is a block diagram which shows an example of a structure by the side of the network of the radio | wireless communications system of FIG. It is a block diagram which shows the example of a hardware constitutions of the object base station which concerns on this Embodiment. It is a block diagram showing the function and composition of a central processing control device concerning this embodiment. It is a data structure figure which shows an example of the SV codebook holding | maintenance part of FIG. It is a block diagram which shows the function and structure of the object base station which concern on this Embodiment. It is a chart which shows the flow of a series of processes in the radio | wireless communications system which concerns on this Embodiment. It is a block diagram which shows the function and structure of the central processing management apparatus which concern on a 1st modification. It is a chart which shows the flow of a series of processes in the radio | wireless communications system which concerns on a 1st modification. It is a block diagram which shows the function and structure of a typical terminal device.

  Hereinafter, the same or equivalent constituent elements, members, and processes shown in the respective drawings are denoted by the same reference numerals, and redundant description will be appropriately omitted.

  FIG. 1 is a schematic explanatory view for explaining the principle of the embodiment. The wireless communication system 10 according to the present embodiment includes, for example, three base stations (base station devices) 2, 4 and 6 each operating as a wireless communication device, and six user terminals 8 a to 8 f. The first base station 2, the second base station 4, and the third base station 6 are arranged adjacent to each other. Two user terminals 8a and 8b exist in the communicable first range (first cell) 2a of the first base station 2, and each of them establishes a radio link with the first base station 2. Therefore, the serving base stations of the first user terminal 8 a and the second user terminal 8 b are all the first base station 2. Similarly, the third user terminal 8c and the fourth user terminal 8d are within the communicable second range 4a of the second base station 4, and the second base station 4 is the serving base station, and the fifth user terminal 8e and the fourth user terminal 8e are The six user terminals 8 f are in the communicable third range 6 a of the third base station 6 and set the third base station 6 as a serving base station. Hereinafter, a user terminal in which a certain base station is a serving base station is referred to as a user terminal belonging to the base station.

  Although a system including three base stations and six user terminals is illustrated as an example, a plurality of these communication devices may exist. The present wireless communication system 10 is, for example, a cellular communication system such as Long Term Evolution (LTE), but may be a cellular communication system of a later generation or a wireless communication system such as a wireless LAN. That is, the following technology can be applied when performing communication based on scheduling between two communication apparatuses, and the target is not necessarily limited to a specific system such as a cellular communication system.

  FIG. 2 is a block diagram showing an example of the configuration of the network side of the wireless communication system 10 of FIG. The wireless communication system 10 includes a central processing and control unit 12. The first base station 2, the second base station 4, the third base station 6, and the central processing manager 12 are connected to one another. The central processing unit 12 may be an entity different from the base station, may be included in the base station, or may itself be a single base station.

  Returning to FIG. 1, during normal operation, each base station 2, 4, 6 independently determines its own UL (Uplink) scheduling information and DL (Downlink) scheduling information. Each of the base stations 2, 4 and 6 notifies the user terminal belonging to itself of the allocation unit of the radio resource allocated to the terminal according to the determined UL and DL scheduling information.

  The allocation unit of radio resources is the smallest unit of radio resources that can be allocated to the user terminal. For example, in LTE, even if a two-dimensional (time-frequency) unit consisting of a resource block (Resource Block), that is, a frequency interval of 12 subcarriers and a time interval of 1 subframe (2 slots) is adopted as an allocation unit. Good. Hereinafter, in order to make the description easy to understand, the case where the above-described resource block is adopted as an allocation unit in UL schedule information will be described. However, it is understood by those skilled in the art that the same argument as the following discussion holds even when other transmission schemes and other allocation units are adopted. For example, multiple resource blocks may be adopted as one allocation unit. In particular, a group consisting of four resource blocks may be adopted as an allocation unit. Alternatively, when Universal-Filtered OFDM is employed, a subband may be employed as an assignment unit.

  In the present embodiment, a training period different from the normal operation period is employed. In the training period, the central processing manager 12 determines UL scheduling information of each base station 2, 4, 6 such that the UL scheduling information has a predetermined relationship. This UL scheduling information indicates allocation of uplink resource blocks in the training period to the user terminal. Assuming that the number of available resource blocks in the training period is N (N is a natural number), in the central processing manager 12, a scheduling vector (Scheduling Vector, SV) which is a vector of N elements for each user terminal ) Is determined. Each element of the scheduling vector corresponds to one of N resource blocks. The elements of the scheduling vector and the resource blocks are in a one-to-one relationship. For example, when only the n (n is a natural number less than or equal to N) resource block is allocated to a user terminal, the scheduling vector of the user terminal is that the nth element is “1” and the other elements are “0” Is a vector.

The central processing manager 12 determines the scheduling vectors of the first to sixth user terminals 8a to 8f belonging to the three base stations 2, 4 and 6 such that the scheduling vectors become linearly independent. The central processing unit 12 arranges the scheduling vectors of the user terminals belonging to each base station to generate a scheduling matrix (Scheduling Matrix) of the base station. In FIG. 1, examples S ₁ , S ₂ and S ₃ of scheduling matrices of the first base station 2, the second base station 4 and the third base station 6 when N = 6 are shown. Each column of the scheduling matrix of a base station is a scheduling vector of user terminals belonging to that base station. For example, the second column of the scheduling matrix S ₃ of the third base station 6 is a schedule vector SV sixth user terminal 8f belonging to the third base station 6. The central processing manager 12 notifies each base station 2, 4, 6 of the scheduling matrix determined for that base station. It is understood by those skilled in the art that the arrangement of scheduling vectors in the scheduling matrix shown in FIG. 1 is an example and can be arbitrarily rearranged.

The central processing manager 12 determines the interference source matrix of the first base station 2 by combining the scheduling matrices S ₂ and S ₃ of the remaining two base stations 4 and 6. Therefore, the columns of the interference source matrix of the first base station 2 consist of the scheduling vectors of the user terminals belonging to the remaining two base stations 4 and 6. The central processing manager 12 similarly determines the interference source matrix of the second base station 4 and the interference source matrix of the third base station 6. The interference source matrix determined in this manner is a full rank matrix because it consists of linearly independent vectors. In FIG. 1, [S ₂ , S ₃ ] indicated by a symbol ISM 1 is an interference source matrix of the first base station 2. The interference source matrix is configured by arranging scheduling vectors of the third user terminal 8c belonging to the second base station 4, the fourth user terminal 8d, and the fifth user terminal 8e belonging to the third base station 6, and the sixth user terminal 8f. Is a full rank matrix of 6 rows and 4 columns. Similarly, [S ₁ , S ₃ ] denoted by symbol ISM 2 is the interference source matrix of the second base station 4, and [S ₂ , S ₁ ] denoted by symbol ISM 3 is the interference source matrix of the third base station 6. It is.

  Each base station 2, 4, 6 schedules the user terminal belonging to itself according to the notified scheduling matrix. In particular, each base station 2, 4, 6 notifies the user terminal belonging to itself of the resource block allocated to the user terminal based on the notified scheduling matrix. The user terminal transmits data wirelessly to the serving base station using the notified resource block. In the example of FIG. 1, the first user terminal 8a and the second user terminal 8b each transmit data to the first base station 2 using the resource blocks assigned thereto (symbols 7a and 7b). The same applies to the other user terminals 8c, 8d, 8e and 8f. The data transmitted by each user terminal may be the same data for identifying an interference source. Data transmitted by one user terminal using different resource blocks may also be data for identifying the same interference source.

  Each of the base stations 2, 4, 6 acquires, for each resource block, information on the power of the remaining part of the received signal excluding the component of the signal transmitted by the user terminal serving as the serving base station. In particular, each base station 2, 4, 6 specifies the remaining part of the power as the received interference power in the resource block. The received interference power in the resource block includes power due to interference from at least one user terminal that transmits data using the resource block among user terminals belonging to other base stations. In the example of FIG. 1, the third user terminal 8c belonging to the second base station 4, the fourth user terminal 8d, the fifth user terminal 8e belonging to the third base station 6, the sixth user terminal 8f to the first base station 2 The arriving signals (i.e. interference signals) are indicated by dashed arrows 7c, 7d, 7e, 7f. The specified power may include effects due to thermal noise, fading and the like other than the interference component, but in the present specification, a case where these effects can be neglected by, for example, averaging and the like will be described.

  In the radio communication system 10 according to the present embodiment, since each base station 2, 4, 6 follows the UL scheduling information determined by the central processing manager 12, the reception interference power in a certain resource block of a certain base station is It can be determined which user terminal of another base station originates. Therefore, it is possible to evaluate the degree of interference from user terminals of other base stations by reversely acting UL scheduling information on received interference power.

In the example of FIG. 1, the individual interference power which is the interference power from the third user terminal 8c to the first base station 2 is denoted as IP3. IP3 is constant across resource blocks allocated to the third user terminal 8c. That is, in each of the second, third and sixth resource blocks, the reception interference power of the first base station 2 includes the same IP3 component. Similarly, the individual interference power from the fourth user terminal 8 d, the fifth user terminal 8 e, and the sixth user terminal 8 f to the first base station 2 is denoted as IP4, IP5, and IP6, respectively. A vector whose element is an individual interference power from a user terminal belonging to another base station to a base station to be calculated is defined as an individual interference power vector Pi (= (IP3, IP4, IP5, IP5) ^T ). The reception interference powers of the first base station 2 in the first to sixth resource blocks are denoted as RIP1 to RIP6, respectively. A vector (= (RIP1, RIP2, RIP3, RIP4, RIP5) in which each element is a corresponding received interference power of N = 6 resource blocks is a reception interference power vector Pri consisting of N = 6 elements. , RIP6) defined as ^T ). At this time, the following equation 1 is established.
Pri = ISM 1 · Pi ... (Equation 1)
Note that “·” represents a matrix product.

したがって、個別干渉電力ベクトルＰｉは以下のように求まる。

Since ISM1 is a full rank matrix, an inverse matrix exists in (ISM1 ^T · ISM1). Therefore, by multiplying both sides of Expression 1 from the left by ISM1 ^T and further multiplying the above inverse matrix from the left,
Pi = (ISM1 ^T · ISM1) ⁻¹ ·· ISM1 ^T · Pri (Equation 2)
Is established. By calculating this equation 2, the individual interference power vector Pi can be determined from the reception interference power vector Pri. A specific calculation example of the individual interference power vector in the case of FIG. 1 is shown below.
“(ISM1 ^T · ISM1) ⁻¹ · ISM1 ^T ” is obtained as follows.

Therefore, the individual interference power vector Pi can be obtained as follows.

  Therefore, the individual interference powers IP3, IP4, IP5, and IP6 are obtained from the reception interference powers RIP1 to RIP6 which are each represented in the form of a linear combination of the individual interference powers. Thereby, for example, as a result of calculation, the central processing management apparatus 12 can specify the user terminal having the largest individual interference power as the main inter-base station uplink interference source of the first base station 2. A process may be performed to reduce or remove uplink interference from the identified interference source. Such processing may be implemented using known uplink interference reduction and cancellation techniques.

  Although FIG. 1 illustrates the case where the number of base stations is three and two user terminals belong to each base station, the technical idea according to the present embodiment is an arbitrary number of base stations and an arbitrary number of users. It will be apparent to those skilled in the art, as mentioned herein, that it is also applicable to systems having terminals. In particular, since it is unlikely that the main inter-basestation uplink interference source to a certain base station belongs to a base station other than the adjacent base station of that base station, it includes a certain base station and a base station adjacent to that base station. It is enough to consider the system. Further, although the number N of resource blocks to be used is six in the example of FIG. 1, the number of user terminals that can be supported (= the number of elements of the scheduling vector) can be increased by increasing N accordingly. On the other hand, since the elements of the vector are binary, the amount of operation for calculating the inverse matrix can be kept small enough. The number of base stations adjacent to a certain base station is limited, the total number of user terminals belonging to those adjacent base stations is also limited, and the number of available resource blocks can be adjusted by adjusting the length of the training period. Can be increased arbitrarily, so that the linear independence of the scheduling vector is secured.

  In the following, focusing on one target base station, an inter-base-station uplink interference source from the adjacent base station adjacent to the target base station to the target base station is identified. In this case, it is possible to specify the inter-base station uplink interference source for all base stations by sequentially selecting the base stations included in the network and repeating the same specifying process. Also, as described later, if linear independence of scheduling vectors is secured between adjacent base stations, linear independence of the scheduling vector of the target base station and the scheduling vector of the adjacent base stations is not required.

  However, when the scheduling vector of the target base station and the scheduling vector of the adjacent base station are determined to be linearly independent, the base station and the adjacent base station simultaneously generate an inter-base station uplink interference source to each base station. It can be identified. In this case, even if the number of base stations increases, the interference source matrix can be made full rank for any base station by allocating the same set of scheduling vectors for distant base stations, that is, non-adjacent base stations. it can. Assignment of this set of scheduling vectors results in graph coloring problems. That is, each base station may be used as a vertex, and vertex coloring of a plane graph in which an edge is provided between each base station and its adjacent base station, in particular, optimum coloring may be solved. In particular, it may impose a requirement that not only adjacent vertices but also vertices further adjacent to a vertex adjacent to a certain vertex and the original vertex must have different colors. A set of linearly independent scheduling vectors is created in advance, the set is divided into chromatic subsets, and each subset is assigned to a corresponding color. Then, a scheduling vector included in a subset corresponding to the color is assigned to a user terminal belonging to a vertex of a certain color (= base station). This makes it possible to reuse scheduling vectors and to suppress the increase in the number of necessary scheduling vectors even if the number of base stations increases. As a result, the scalability of the method according to the present embodiment is enhanced. The solution for vertex coloring may be obtained using a computer or the like as appropriate. For example, when considering a system consisting of ideal hexagonal cells, seven colors are sufficient.

  FIG. 3 is a block diagram showing an example of the hardware configuration of the target base station 100. As shown in FIG. The adjacent base station has the same configuration as the target base station. In one example, the target base station 100 has a hardware configuration as shown in FIG. 3, and includes, for example, a CPU 201, a ROM 202, a RAM 203, an external storage device 204, and a communication device 205. In the target base station 100, for example, a program for realizing each function of the target base station 100, which is recorded in any of the ROM 202, the RAM 203, and the external storage device 204, is executed by the CPU 201. Then, the target base station 100 controls the communication device 205, for example, by the CPU 201, and performs central processing between the target base station 100 and another base station, or between the target base station 100 and the user terminal, or the target base station 100. Communication with the management device 12 is performed. In FIG. 3, although the target base station 100 includes one communication device 205, for example, the target base station 100 is for communication with a communication device for communication between base stations and a user terminal. And a communication device for communication with the central processing management device 12.

  The target base station 100 may be provided with dedicated hardware for executing each function, or may execute a part of the hardware and a computer that operates a program to execute the other part. Also, the target base station 100 may execute all the functions by a computer and a program. Further, the central processing management device 12 may have basically the same hardware configuration as the target base station 100. The central processing management device 12 controls the communication device to perform communication between the central processing management device 12 and each base station that it manages. When the central processing management device 12 is included in the target base station 100, communication between the central processing management device 12 and the target base station 100 is by an internal interface.

  FIG. 4 is a block diagram showing the function and configuration of the central processing management device 12 according to the present embodiment. The central processing management device 12 includes a network information acquisition unit 102, a scheduling determination unit 104, an ISM generation unit 106, a notification unit 108, a network information storage unit 110, and an SV codebook storage unit 118. The network information acquisition unit 102 acquires information on the network topology on the network side of the wireless communication system 10 from another network element or the like. The information on the network topology includes the physical positional relationship of the base stations included in the wireless communication system 10. The network information acquisition unit 102 may acquire only information on a base station managed by the central processing management device 12. The network information acquisition unit 102 acquires, for each base station, a terminal ID for specifying a user terminal belonging to the base station from a Home Subscriber Server (HSS) or the like. The network information acquisition unit 102 registers the acquired information in the network information storage unit 110.

  FIG. 5 is a data structure diagram showing an example of the SV codebook holding unit 118 of FIG. The SV codebook holding unit 118 holds a set of predetermined linearly independent scheduling vectors. The SV codebook holding unit 118 holds an index, which is an identifier for uniquely identifying a scheduling vector, the scheduling vector, and a color ID for identifying a subset of a color to which the scheduling vector belongs, in association with each other. The information held in the SV codebook holding unit 118 may be created in advance by a network manager or the like based on the number of available resource blocks. Color ID relates to the reuse of scheduling vectors in the other aspects described above.

  Returning to FIG. 4, the scheduling determination unit 104 determines UL scheduling information in the training period. The scheduling determination unit 104 includes a base station selection unit 112, a user terminal identification unit 114, and an SV allocation unit 116. The base station selection unit 112 selects a target base station 100 that requires identification of an uplink inter-base station uplink interference source. The target base station 100 may be any of the first base station 2, the second base station 4, and the third base station 6. The base station selection unit 112 refers to the physical positional relationship of the base stations held in the network information holding unit 110, and selects a plurality of adjacent base stations adjacent to the target base station 100.

  The user terminal identification unit 114 refers to the correspondence between the base station and the terminal ID held in the network information holding unit 110, and belongs to the target base station 100 selected by the base station selection unit 112 and a plurality of adjacent base stations. Identify multiple user terminals.

  The SV assignment unit 116 refers to the SV codebook holding unit 118, and assigns different scheduling vectors to each of the plurality of user terminals identified by the user terminal identification unit 114. Since the scheduling vectors held in the SV codebook holding unit 118 are linearly independent, the plurality of scheduling vectors assigned to the plurality of user terminals are also linearly independent.

  The ISM generation unit 106 generates an interference source matrix for the target base station 100 by combining the plurality of scheduling vectors allocated to the plurality of user terminals belonging to the plurality of adjacent base stations by the SV allocation unit 116.

  The notification unit 108 notifies the target base station 100 and a plurality of adjacent base stations of the UL scheduling information determined by the scheduling determination unit 104. The notification unit 108 controls the UL scheduling information including the terminal ID of the user equipment belonging to the base station and the index of the scheduling vector assigned to the user equipment in each of the target base station 100 and the plurality of adjacent base stations as a control message. Send as. In this case, the amount of communication can be reduced compared to the case of transmitting the scheduling vector itself. The notification unit 108 transmits the interference source matrix generated by the ISM generation unit 106 to the target base station 100. This interference source matrix is included in the control message. Alternatively, the notification unit 108 may transmit a set of scheduling vector indices included in the interference source matrix in order to notify the target base station 100 of the interference source matrix. In this case, the amount of communication can be reduced. As the number of resource blocks in the training period increases and the number of elements of the scheduling vector also increases, the amount of reduction in traffic is higher. For example, if the number of resource blocks is 100, while the scheduling vector itself is about 100 bits, the index may be 7 bits.

  FIG. 6 is a block diagram showing the function and configuration of the target base station 100. As shown in FIG. Other base stations may have the same function and configuration as the target base station 100. The target base station 100 has a data structure equivalent to that of the control message acquisition unit 120, the scheduler 122, the base station communication unit 124, the reception interference power acquisition unit 126, the evaluation unit 128, and the SV codebook holding unit 118. And a base station SV codebook holding unit 130. The base station SV codebook holding unit 130 may be appropriately updated by the central processing management device 12 so as to correspond to the SV codebook holding unit 118. The control message acquisition unit 120 acquires the control message addressed to the target base station 100 received from the notification unit 108 of the central processing management device 12, and scheduling assigned from the acquired control message to the user terminal belonging to the target base station 100. Extract the vector index and the interference source matrix.

  The scheduler 122 refers to the base station SV codebook holding unit 130 and specifies a scheduling vector corresponding to the index extracted by the control message acquiring unit 120. The scheduler 122 generates terminal-destined control information including information specifying the uplink resource block assigned to the user terminal belonging to the target base station 100 based on the identified scheduling vector.

  The base station communication unit 124 wirelessly transmits the terminal-destined control information generated by the scheduler 122 via the downlink control channel such as PDCCH (Physical Downlink Control CHannel, physical downlink control channel) to each target base station 100. Send to user terminal. The terminal-addressed control information may be transmitted on a data channel such as PDSCH (Physical Downlink Shared CHannel). Base station communication section 124 wirelessly transmits uplink data signals transmitted from each user terminal according to terminal-destined control information via an uplink shared channel such as PUSCH (Physical Uplink Shared CHannel). Receive on The base station communication unit 124 exchanges control information and data with the user terminal in various other manners, which may be realized using a known communication technology.

  The reception interference power acquisition unit 126 acquires reception interference power for each resource block in the training period. The reception interference power acquisition unit 126 specifies, for the resource block to be calculated, among the user terminals belonging to the target base station 100, the user terminal allocated to the resource block to be calculated. The reception interference power acquisition unit 126 specifies the component of the signal received by the base station communication unit 124 via the PUSCH from the specified user terminal in the resource block to be calculated. The reception interference power acquisition unit 126 calculates the power of the remaining portion obtained by subtracting the component of the specified signal from the total signal received by the base station communication unit 124 via the PUSCH in the resource block to be calculated. The reception interference power of the resource block to be calculated is acquired. Note that, when the user terminal is not assigned to the resource block to be calculated, the reception interference power acquisition unit 126 receives the interference of the total signal power received by the base station communication unit 124 via the PUSCH in the resource block to be calculated. Obtain as power.

  The evaluation unit 128 targets the user terminals belonging to any of a plurality of adjacent base stations based on the interference source matrix extracted by the control message acquisition unit 120 and the reception interference power acquired by the reception interference power acquisition unit 126. The interference to the base station 100 is evaluated. The evaluation unit 128 includes a matrix operation unit 132 and an interference source identification unit 134.

The matrix operation unit 132 calculates a matrix to be applied to the reception interference power vector including the reception interference power acquired by the reception interference power acquisition unit 126 from the interference source matrix extracted by the control message acquisition unit 120. When the interference source matrix is expressed as ISM, the matrix operation unit 132 executes the following matrix operation.
(ISM ^T · ISM) ^-1 · ISM ^T
The matrix operation unit 132 may execute the above operation before or during the start of the training period, and hold the result. In this case, the time taken to evaluate interference after the period can be shortened.

  The interference source identification unit 134 operates the individual interference power vector by causing the matrix obtained as a result of the matrix operation in the matrix operation unit 132 to act on the reception interference power vector. The interference source identification unit 134 identifies the user terminal corresponding to the largest element among the elements included in the calculated individual interference power vector as the main inter-base station uplink interference source for the target base station 100. The interference source identification unit 134 may rank the interference sources based on the magnitudes of the elements of the individual interference power vector.

The operation of the wireless communication system 10 having the above configuration will be described.
FIG. 7 is a chart showing the flow of a series of processes in the wireless communication system 10. The central processing management apparatus 12 acquires information on the network topology and user terminals belonging to the base station (S702). The central processing manager 12 determines UL scheduling information for the target base station 100 and the adjacent base stations, and an interference source matrix for the target base station 100 (S704). The central processing manager 12 transmits a control message CM including the determined information to the target base station 100 (S706). The target base station 100 generates terminal address control information for the user terminal belonging to the target base station 100 based on the received control message CM (S 708). The target base station 100 transmits the generated terminal-addressed control information to the user terminal (S710). The user terminal transmits data to the target base station 100 using the resource block specified by the received terminal-destined control information addressed to the own terminal in the training period TR (S712, S714, S716). The target base station 100 measures the reception interference power for each resource block in the training period TR (S718, S720, S722). The target base station 100 identifies the inter-base station uplink interference source based on the measured reception interference power and the interference source matrix notified by the control message IM (S724).

  According to radio communication system 10 according to the present embodiment, it is possible to specify the inter-base station uplink interference source directly from the measurement value of the uplink power in target base station 100. Therefore, the specific accuracy is improved as compared with the case of indirectly estimating the uplink interference source from the downlink information. This is applicable especially when path loss characteristics differ between uplink and downlink such as FDD (Frequency-Division Duplex).

  In addition, the process of identifying the interference source is performed on the network side, and it is not necessary for the user terminal to have a dedicated function or to perform a dedicated process. Therefore, the interference source can be identified without increasing the load on the resources such as the battery and the computing function of the user terminal. This is especially applicable to applications in which the restriction on the battery and arithmetic function of the terminal such as MCT (Machine Type Communication) is severe.

  Further, in the radio communication system 10 according to the present embodiment, by selecting scheduling vectors independently, it is possible to obtain individual interference power from user terminals of adjacent base stations by relatively simple matrix calculation.

  On the other hand, for example, Non-Patent Document 4 discloses a technique of estimating uplink interference sources using downlink RSRP (Reference Signal Received Power). In the technology described in Non-Patent Document 4, the user terminal measures downlink Path Loss for each of the serving base station and its adjacent base station, and transmits the measurement result to the serving base station. In path loss measurement, the user terminal needs to execute relatively complicated processing such as successive interference cancellation in order to specify the contribution from each base station. However, implementing such a process may increase the cost of the user terminal or may increase the power consumption at the user terminal.

  Therefore, adopting the technology according to the present embodiment makes it possible to obtain individual interference power more easily and regardless of the resource on the user terminal side, as compared to the case where interference cancellation is used in the user terminal one by one.

  Further, in the radio communication system 10 according to the present embodiment, the central processing management device 12 determines UL scheduling information of each base station. Therefore, this is compatible with the scheme of centrally managing the base stations by the central processing unit 12.

  The configuration and the operation of the wireless communication system 10 according to the embodiment have been described above. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to the combination of each component and each processing, and such modifications are also within the scope of the present invention.

  Although the embodiment has described the case where the central processing management device 12 determines UL scheduling information, the present invention is not limited to this. For example, each base station may independently determine base station scheduling information indicating allocation of resource blocks to user terminals belonging to the own base station.

  FIG. 8 is a block diagram showing the function and configuration of the central processing management device 312 according to the first modification. The central processing management device 312 includes a network information acquisition unit 102, a scheduling collection unit 314, a lossless identification unit 316, an ISM generation unit 106, a notification unit 318, a network information storage unit 110, and an SV codebook storage unit 118. And. The scheduling collection unit 314 collects base station scheduling information uniquely set from each base station. The lossless identification unit 316 identifies a set of base stations whose schedule vectors are linearly independent based on the collected base station scheduling information. The notification unit 318 requests each of the base stations included in the identified set to perform interference evaluation.

  FIG. 9 is a chart showing the flow of a series of processes in the wireless communication system according to the first modification. Each of the plurality of base stations managed by the central processing management device 312 determines base station scheduling information independently of other base stations based on its own state and network conditions (S802). The base station scheduling information is expressed by assigning a schedule vector to the user terminal, and may be, in particular, a set of scheduling vectors. Each base station transmits the determined base station scheduling information to the central processing manager 312 (S804). From the received base station scheduling information, the central processing manager 312 specifies, as a reversible system, a set of base station scheduling information constituting an interference source matrix capable of the above matrix calculation (S806). In particular, central processing unit 312 finds a set of base station scheduling information that constitutes a set of linearly independent scheduling vectors. This is realized by verifying whether or not the scheduling vector contained in the combination is linearly independent with respect to possible combinations of received base station scheduling information, and in particular may be realized by a computer algorithm . The central processing manager 312 transmits, to each base station included in the identified reversible system, a control message CM 'that includes an interference source matrix for that base station and requests an evaluation of interference (S808). After that, the same processing as the processing shown in FIG.

  According to the wireless communication system of the first modification, the base station scheduling information is determined according to the state and condition of the base station itself, so that the communication efficiency and the throughput are compared with the case where the central processing management device 12 determines the scheduling information. It is advantageous in terms of However, since the reversible system may not be found, the method of the embodiment is advantageous in terms of the identification of the interference source.

  In step S408, the control message CM 'may be transmitted to a base station not included in the reversible system. Also in this case, it is possible to evaluate inter-base station uplink interference from base stations included in the reversible system to base stations not included.

  Although the embodiment has described the case where the target base station 100 identifies the inter-base station uplink interference source, the present invention is not limited to this. For example, the target base station may notify the central processing unit of the measured reception interference power. The central processing management device may perform the same processing as the processing in the evaluation unit 128 based on the received interference power and interference source matrix notified, and may specify the inter-base station uplink interference source. In this case, since it is only necessary to provide one central processing management device with one operation resource for performing matrix operation for interference source identification and magnitude comparison of vector elements instead of providing each base station, the device configuration on the network side It can be simplified more.

  In the embodiment, a plurality of scheduling vectors allocated to a plurality of user terminals belonging to the target base station 100 and a plurality of user terminals allocated to a plurality of adjacent base stations are allocated by the SV allocation unit 116. Although the case where the scheduling vector and are linearly independent has been described, it is not limited thereto. In principle of calculation, the plurality of scheduling vectors assigned to the plurality of user terminals belonging to the target base station 100 is not limited. That is, if the plurality of scheduling vectors assigned to the plurality of user terminals belonging to the plurality of adjacent base stations are linearly independent, the plurality of scheduling vectors assigned to the plurality of user terminals belonging to the target base station 100 is linearly independent Even if not, it is possible to specify the inter-base station uplink interference source of the target base station 100. For example, the base station of the macro cell may be a target base station, and the base stations of a plurality of small cells around the macro cell may be adjacent base stations. In this case, since it is possible to freely set the scheduling vector of the user terminal belonging to the macro cell while enabling identification of the interference source of the uplink interference from the small cell to the macro cell, the communication performance of the macro cell itself can be maintained excellent.

  Although the embodiment has described the case where the number of adjacent base stations with respect to the target base station 100 is two or more, the present invention is not limited to this. Even when there is only one base station adjacent to the target base station 100, the technical idea according to the present embodiment can be applied. In this case, the interference source matrix of the target base station 100 may be used as the scheduling matrix of the adjacent base station.

  In the embodiment, when a plurality of resource blocks (of different frequency sections) sharing a time section are allocated to user terminals belonging to adjacent base stations, the total is obtained by adding up the individual interference power in those resource blocks. The individual interference power of In this case, more accurate evaluation of the individual interference power is possible.

  FIG. 10 is a block diagram showing the function and configuration of a typical terminal device included in the above-described wireless communication system. This terminal device may be any of the six user terminals 8a to 8f shown in FIG. The hardware configuration of this terminal device conforms to that shown in FIG. The terminal device includes a schedule information acquisition unit 1002 and a wireless transmission / reception unit 1001. The schedule information acquisition unit 1002 acquires schedule information from the serving base station of the terminal apparatus via the downlink control channel. This corresponds to step S710 in FIG. The wireless transmission and reception unit 1001 transmits a signal to the serving base station according to the schedule information acquired by the schedule information acquisition unit 1002. This corresponds to step S712 in FIG.

  2 1st base station, 4 2nd base station, 6 3rd base station, 10 radio communication system.

Claims (8)

A management apparatus of a wireless communication system including a first base station and a second base station, comprising:
An acquiring unit for acquiring information on power of a remaining part excluding a component of a signal transmitted by a terminal using the first base station as a serving base station from a signal received by the first base station;
Based on the schedule information of the second base station and the information related to the power acquired by the acquisition unit, interference from each of the terminals using the second base station as a serving base station to the first base station is performed. and an evaluation unit for evaluation,
The wireless communication system includes a plurality of the second base stations,
The plurality of schedule information of the plurality of second base stations are determined to have a predetermined relationship,
The predetermined relationship is that, when each radio resource is allocated to a plurality of terminals is represented by a vector, the plurality of vectors are linearly independent,
The evaluation unit, the management apparatus characterized that you evaluate interference by performing matrix operation based on linear independence of vectors.   The management apparatus according to claim 1, wherein the first base station is adjacent to the second base station. The evaluation unit, the management apparatus according to claim 1 or 2, characterized in that to identify the terminal as the interference source to the first base station based on the result of the matrix operation. 4. The apparatus according to any one of claims 1 to 3 , further comprising a determination unit configured to determine schedule information of the first base station such that the schedule information and the plurality of schedule information have the predetermined relationship. The management device described in the section. The management apparatus according to any one of claims 1 to 4 , wherein the management apparatus is included in the first base station or the second base station. A terminal having the first base station as a serving base station,
A schedule information acquisition unit that acquires schedule information from the first base station;
A transmitter configured to transmit a signal to the first base station according to the schedule information acquired by the schedule information acquisition unit;
A management apparatus of a wireless communication system including the first base station and the second base station,
Obtaining information related to the power of the remaining part excluding the component of the signal transmitted by the terminal from the signal transmitted by the transmitter and received by the first base station;
The interference from each of terminals using the second base station as a serving base station to the first base station is evaluated based on the schedule information of the second base station and the information on the acquired power ;
The wireless communication system includes a plurality of the second base stations,
The plurality of schedule information of the plurality of second base stations are determined to have a predetermined relationship,
The predetermined relationship is that, when each radio resource is allocated to a plurality of terminals is represented by a vector, the plurality of vectors are linearly independent,
The management apparatus evaluates interference by performing matrix operation based on linear independence of vectors . A method executed by a management device of a wireless communication system including a first base station and a second base station, the method being:
Obtaining information on the power of the remaining part excluding the component of the signal transmitted by the terminal using the first base station as a serving base station from the signal received by the first base station;
Evaluating interference from each of the terminals having the second base station as a serving base station to the first base station based on the schedule information of the second base station and the information on the acquired power; , only including,
The wireless communication system includes a plurality of the second base stations,
The plurality of schedule information of the plurality of second base stations are determined to have a predetermined relationship,
The predetermined relationship is that, when each radio resource is allocated to a plurality of terminals is represented by a vector, the plurality of vectors are linearly independent,
A method characterized in that the evaluating comprises evaluating interference by performing a matrix operation based on linear independence of vectors . In a management device of a wireless communication system including a first base station and a second base station,
A function of acquiring information on power of a remaining part excluding a component of a signal transmitted by a terminal using the first base station as a serving base station from a signal received by the first base station;
A function of evaluating interference from each of terminals using the second base station as a serving base station to the first base station based on schedule information of the second base station and information on acquired power; , to realize the,
The wireless communication system includes a plurality of the second base stations,
The plurality of schedule information of the plurality of second base stations are determined to have a predetermined relationship,
The predetermined relationship is that, when each radio resource is allocated to a plurality of terminals is represented by a vector, the plurality of vectors are linearly independent,
A computer program characterized in that the function to evaluate includes a function to evaluate interference by performing matrix operation based on linear independence of vectors .

Images